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Competition between hydrogen and halogen bonding in the structures of 5,10‐dihydroxy‐5,10‐dihydroboranthrenes
Author(s) -
Durka Krzysztof,
Luliński Sergiusz,
Jarzembska Katarzy.,
Smętek Jaromir,
Serwatowski Janusz,
Woźniak Krzysztof
Publication year - 2014
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520613034987
Subject(s) - halogen , hydrogen bond , halogen bond , crystallography , chemistry , derivative (finance) , crystal structure , isostructural , supramolecular chemistry , stereochemistry , thiophene , crystal (programming language) , crystal engineering , molecule , alkyl , organic chemistry , computer science , financial economics , programming language , economics
X‐ray crystallographic and computational studies are reported for a series of boranthrenes, substituted with halogen atoms. The role of competitive hydrogen (O—H...O, O—H...F, C—H...O) and halogen (Cl...Cl, O...Br, F...F) bonding interactions on the molecular arrangement in the crystal structures is discussed. The structural analysis and calculations reveal that the O—H...O hydrogen bond in the unsubstituted derivative 5,10‐dihydroxy‐5,10‐dihydroboranthrene, C 12 H 10 B 2 O 2 , is of moderate strength ( ca −20 kJ mol −1 ), but weaker than that in the related thiophene derivative 4,8‐dihydro‐4,8‐dihydroxy‐ p ‐diborino[2,3‐ b :5,6‐ b ]dithiophene, C 8 H 6 B 2 O 2 S 2 ( ca −40 kJ mol −1 ). This is due to shielding of the OH group by the H atoms in the β‐position of the boranthrene unit. Structural diversity derived from the flexibility of the O—H...O hydrogen bond facilitates the occurrence of other competitive interactions. For instance, in the 1,6‐difluoro derivative, C 12 H 8 B 2 F 2 O 2 , the crystal packing results from O—H...F and F...F interactions. In turn, the 1,6‐dibromo derivative, C 12 H 8 B 2 Br 2 O 2 , is dominated by Br...O halogen‐bond interactions. In the most interesting case, the 1,6‐dichloro derivative, C 12 H 8 B 2 Cl 2 O 2 , molecular disorder leads to the formation of two different supramolecular arrangements co‐existing in the crystal lattice, one based on the Cl...Cl and C—H...O bonds, and the other stabilized by O—H...O hydrogen bonds. Calculations performed with density‐functional theory (DFT; CRYSTAL09 ) and PIXEL methodologies show that both lattices are characterized by similar energy values ( ca −100 kJ mol −1 ). A mixed arrangement with random or short‐range‐ordered molecular orientations can also be expected.